In networks that are compartmentalized into independent domains (e.g., Automatically Switched Optical Networks (ASONs) and Virtual Private Networks (VPNs)), it is a common technique to virtualize the topology within the domain and then advertise the virtual topology to external domains for path computation purposes. Currently, there are no accepted techniques for linking the virtualized topology with actual resources within the domain, in order to control resource utilization. In fact, the virtual topology is typically assumed to have no relationship to the true topology within the domain, allowing any domain resources to be used regardless of the path computed by the source.
The current approach to virtualization of topology makes it impossible for a carrier to provide meaningful information about the status and utilization of resources within its domain, without advertising the full domain topology. As a result, it is difficult to provide guarantees of connection availability based on the advertised topology. A system and method are needed wherein this meaningful information is provided without advertising the full domain topology.
Interoperability of intelligent optical networks will be enabled by an Exterior Network-Network Interface (E-NNI) with control plane messaging. Standards for this interface are being defined in the ITU-T (Automatically Switched Optical Networks) and the IETF (Generalized Multi-Protocol Label Switching), where the control plane supports both routing protocol and signaling protocol. E-NNI is a control plane messaging interface for ASON.
The ASON E-NNI allows a particular network or control domain to advertise a virtualized topology to other networks or control domains in order to reduce the complexity of advertising and to allow policy control over the information leaked to other networks about the true arrangement of links and nodes within the network. Other networks can then request services from the domain using signaling messages that request particular paths across a domain based on the virtual topology.
These services may be requested originally from either a client device, set up and released by the customer on demand using signaling and routing protocols (in which case it is called a Switched Connection), or a management system interface, set up and released from the management system, which uses network generated signaling and routing protocols to establish the connection (in which case it is called a Soft Permanent Connection), and the requesting entity may be either part of the domain or part of an exterior network or domain.
While these virtualized topologies allow considerable flexibility in how a domain advertises its resources to other networks or domains, it is still important for the domain to implement policies that support some type of control over how it allocates resources for a connection request from another network or domain. In particular, the advertisement of the virtual topology can be manipulated to control aspects of requests from other networks, for example, to indicate to other networks that some paths are temporarily or permanently unavailable and thereby stop other networks from requesting services that would utilize these paths.
Thus, what is needed is a system and a method for abstracting a network topology into virtual links and supporting both generic and instantiated virtualized links for linking a virtualized topology with actual resources within a domain, providing security over network topology information, providing control over the allocation of resources, and reducing the complexity of advertising. Additionally, a system and method are needed wherein this meaningful information is provided without advertising the full domain topology.